Method and apparatus for enabling subscriber stations to process a synchronization channel in a spread spectrum communications system

Abstract

During initiation procedure between subscriber stations and access network adhering to CDMA standards, (e.g., IS-95 and IS-2000) the subscriber station receives a Sync Channel Message. Due to a design/manufacturing error, certain subscriber stations adhering to the IS-95 fail to ignore a portion of the Sync Channel Message, intended for a proper operation of subscriber stations adhering to the IS-2000. This causes a failure of the IS-95 subscriber stations' operation. The disclosed invention describes embodiments allowing the faulty subscriber stations to operate on an access networks build in accordance with both IS-95 and IS-2000 standards.

1 . An apparatus for frequency and channel assignment for sectors in a spread spectrum communications system, the apparatus comprising:
 a processor that modifies a synchronization message to generate a single modified message, the modified message comprises a Protocol Revision (P REV) field and a CDMA Frequency Assignment (CDMA FREQ) field, the synchronization message comprises the modified message and an Extended CDMA Frequency Assignment (EXT CDMA FREQ) field;   a first modulator that modulates the modified message on a first synchronization channel transmitted on at least one first frequency from at least one sector; and   a second modulator that modulates the synchronization message on a second synchronization channel transmitted on at least one second frequency from the at least one sector.   
   
   
       2 . The apparatus of  claim 1 , wherein modulating the modified message on the second synchronization channel transmitted on at least one second frequency from the at least one sector comprises:
 deleting at least one field from the message.   
   
   
       3 . An apparatus for frequency and channel assignment for sectors in a spread spectrum communications system, the apparatus comprising:
 a first modulator that modulates a message on a first synchronization channel transmitted on at least one first frequency from at least one sector; the message comprising:
 a P REV (Protocol Revision) field, 
 a MIN P REV field, 
 a SID field, 
 a NID field, 
 a PILOT PN field, 
 a LC state field, 
 a SYS TIME field, 
 a LP SEC field, 
 a LTM OFF field, 
 a DAYLT field, 
 a PRAT field, 
 a CDMA FREQ (CDMA Frequency Assignment field, and 
 a EXT CDMA FREQ (Extended CDMA Frequency Assignment) field; and 
   a processor that modifies the message thereby forming a modified message; and   a second modulator that modulates the single modified message on a second synchronization channel transmitted on at least one second frequency from the at least one sector.   
   
   
       4 . The apparatus of  claim 3 , wherein:
 the CDMA FREQ field consists of eleven bits; and   the EXT CDMA FREQ field consists of eleven bits.   
   
   
       5 . The apparatus of  claim 3 , wherein modulating the modified message on the second synchronization channel transmitted on at least one second frequency from the at least one sector comprises:
 deleting at least one field, occurring after the CDMA FREQ field, from the message.   
   
   
       6 . An apparatus for frequency and channel assignment for sectors in a spread spectrum communications system, the apparatus comprising:
 means for modifying a synchronization message to generate a single modified message, the modified message comprises a Protocol Revision (P REV) field and a CDMA Frequency Assignment (CDMA FREQ) field, the synchronization message comprises the modified message and an Extended CDMA Frequency Assignment (EXT CDMA FREQ) field;   means for modulating the modified message on a first synchronization channel transmitted on at least one first frequency from at least one sector; and   means for modulating the synchronization message on a second synchronization channel transmitted on at least one second frequency from the at least one sector.   
   
   
       7 . An apparatus for frequency and channel assignment for sectors in a spread spectrum communications system, the apparatus comprising:
 means for modulating a message on a first synchronization channel transmitted on at least one first frequency from at least one sector; the message comprising:
 a P REV (Protocol Revision) field, 
 a MIN P REV field, 
 a SID field, 
 a NID field, 
 a PILOT PN field, 
 a LC state field, 
 a SYS TIME field, 
 a LP SEC field, 
 a LTM OFF field, 
 a DAYLT field, 
 a PRAT field, 
 a CDMA FREQ (CDMA Frequency Assignment field, and 
 a EXT CDMA FREQ (Extended CDMA Frequency Assignment) field; and 
   means for modifying the message thereby forming a modified message; and   means for modulating the single modified message on a second synchronization channel transmitted on at least one second frequency from the at least one sector.   
   
   
       8 . A method for frequency and channel assignment for sectors in a spread spectrum communications system, the method comprising:
 determining a first portion of a synchronization message, the first portion of the synchronization message is usable by devices compatible with a first communication standard and the entire synchronization message is usable by devices compatible with a second communication standard;   modulating the first portion of the synchronization message on a first synchronization channel transmitted on at least one first frequency from at least one sector; and   modulating the entire synchronization message on a second synchronization channel transmitted on at least one second frequency from the at least one sector.   
   
   
       9 . The method of  claim 8 , further comprising:
 receiving an indication from at least one device compatible with the second communication standard; and   transmitting an redirection message to each of the at least one device compatible with the second communication standard.   
   
   
       10 . The method of  claim 9 , wherein the redirection message comprises information directing the at least one device to tune to a particular frequency. 
   
   
       11 . A method for frequency and channel assignment for sectors in a spread spectrum communications system, the method comprising:
 means for determining a first portion of a synchronization message, the first portion of the synchronization message is usable by devices compatible with a first communication standard and the entire synchronization message is usable by devices compatible with a second communication standard;   means for modulating the first portion of the synchronization message on a first synchronization channel transmitted on at least one first frequency from at least one sector; and   means for modulating the entire synchronization message on a second synchronization channel transmitted on at least one second frequency from the at least one sector.   
   
   
       12 . A computer program product comprising:
 a computer-readable medium comprising:
 code for causing a computer to determine a first portion of a synchronization message, the first portion of the synchronization message is usable by devices compatible with a first communication standard and the entire synchronization message is usable by devices compatible with a second communication standard; 
 code for causing a computer to modulate the first portion of the synchronization message on a first synchronization channel transmitted on at least one first frequency from at least one sector; and 
 code for causing a computer to modulate the entire synchronization message on a second synchronization channel transmitted on at least one second frequency from the at least one sector.